Thanks @jax200 - that’s super helpful. I’ve managed to calibrate the GPS and compass now. The ESCs are still not calibrating, and after a single run of not having the yellow flashing light on the Pixhawk, it’s back to flashing yellow each time again - but it still feels like it is a small step in the right direction, so thank you!
Re getting the ESC to calibrate, it feels like it may be linked with a myriad of other oddities my drone is displaying (at least compared to what I’m seeing in the video tutorials), so I’ll create a new thread in case they all related.